Going to try put the entire experience into consideration here.. from least to greatest
- Generation 2 -
I can mostly narrow it down to one factor. I really did not care for the Art Design in the slightest. Generation 1 was weird and all with their Birds with 3 heads and Tongue Monsters.. but it was kind of established that these creatures existed in some form of Eco-System where they adapted these things for a purpose. When I look at pokemon like Azumarill, and it tells me its some kind of Rabbit.. with a wave pattern and bubbles on it's fur.. its kind of like turning the concept on its head. Its not quite the same thing as before, if that makes any sense. And you only find weird crap like this in Gen 2 Pokemon. The legendary trio are another good example of this. I guess what I'm saying is, its too cartoony looking of all the cartoon critters I've seen.. and not in the good way.
- Generation 1 -
It's iconic, but it's also the most unbalanced and extremely glitchy if we're talking about the original Generation 1. Psychics killing everything kind of ruins the fun a bit.. And it's not that I'd say the art design is bad, it's got some of my favorites in it.. but its more filled with old redundancies that don't fit in with what Modern Day Pokemon has become.. Kangaskhan babies always hatching with babies of their own in their pouch.. Cubone's apparent endless Orphan-itude.. It was a fun romp, but it wasn't the most thought out.. and generally speaking, thats how first runs usually are.
- Generation 5 -
It's mostly guilty of one thing that kind of ruins the entire experience with me.. and thats trying to make a Pokemon Story seem epic, and failing miserably at it. I'm a lore guy.. I write my own stories, its one of my passions in life. If you want to create something meaningful and thought provoking, one must first treat their readers and their own story with some amount of respect. Black and White fails to do just that.. and fails HARD at it. I face palm every time N, or Ghetis or Team Plasma show up because they act so ALIEN. I can go on and on about how stupid this game's story is, but I'd be here all day ranting about it like Spoony on Final Fantasy 13.. That being said though, the art design didn't bug me quite as much (Oh noes a Trash Bag and an Ice Cream cone!) and I liked the fact that it featured animated sprites. If this game was a little more self aware at how retarded it was.. it would probably be one of my favorites.. but if I can't stand to listen to it prattle on like it does, then it is what it is.
- Generation 3 -
To be honest, I don't remember much about this generation, which is probably why I'm putting it here. One of the first things I remembered about generation 3 the first time seeing it was how colorful it was and how much NOT it was like Generation 2.. and I think thats probably why I've taken such a liking to the Art Design. This is what a Pokemon SHOULD look like. That being said, I never finished R/S/E .. and right now I just can't be bothered, so I'll let that slide for now.
- Generation 4 -
There was a lot of new things in this generation that I liked. Some care was given to some older Pokemon to make them less crappy.. some we weren't really expecting. The art design was passable, the story was interesting enough, and the evil team wasn't as ever present and ridiculous.. well, no more than usual anyway. It did have a lot of filler Pokemon that weren't particularly useful, many of them kind of forgettable. Burmy, I kid you not, is one of many in this generation that I forget ever existed. I'd have to say though, the Legendary guys in this game were some of the most bizarre looking things ever put to paper. But I guess when you're dealing with time and space, you would probably create something completely alien.
- Generation 6 -
Kind of scratches all the itches. It's a 3d Pokemon game, though the models barely move (hopefully that changes as the games press forward) .. it's got a plethora of back logged old Pokemon from all the previous generations with easy access to your favorites. It's breeding mechanics and EV training mechanics are fleshed out and simple to follow. The story line actually invoked feelings from me, which is a complete first.. a feeling of sympathy every time my rival challenged me and was forced to curb stomp them.. which clearly means they got their act together since Gen 5.. the evil team was hilarious and knew that they were a joke for the most part.. (I only had issue with Team Flare when I had to take them seriously, which was haaarrd) no filler Pokemon, with some hidden gems in Diggersby and Talonflame. Easy access to trade online, a useable GTS .. Totally down with Gen 6.